Pharmacology and Drug Interactions

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Questions and Answers

What is the primary mechanism of action of aspirin in relation to platelet aggregation?

Inhibition of platelet activation

Reversible inhibition of thromboxane A2 synthesis

Stimulation of thromboxane A2 synthesis

Irreversible inhibition of thromboxane A2 synthesis (correct)

What is the effect of aspirin on gastric mucosa?

It protects the gastric mucosa from irritation

It stimulates the production of gastric mucus

It irritates the gastric mucosa, causing epigastric distress (correct)

It has no effect on the gastric mucosa

What is the effect of long-term intake of large doses of aspirin on clotting factors?

It stimulates the production of vitamin K

It has no effect on clotting factors

It decreases the synthesis of clotting factors in the liver (correct)

It increases the synthesis of clotting factors in the liver

What is the duration of aspirin's effect on platelet aggregation?

About a week Signup and view all the answers

What is the therapeutic effect of aspirin in analgesic doses?

Only analgesic and antipyretic effects Signup and view all the answers

What is the effect of aspirin on bleeding time?

It increases bleeding time Signup and view all the answers

What is the pharmacological action of salicylic acid released from aspirin?

Analgesic, antipyretic, and anti-inflammatory actions Signup and view all the answers

What is the effect of prophylactic vitamin K therapy on bleeding risk associated with long-term aspirin intake?

It decreases the bleeding risk Signup and view all the answers

What is the limiting factor in the absorption of aspirin?

Poor water solubility Signup and view all the answers

What is the plasma half-life of aspirin, considering its conversion to salicylic acid?

3-5 hours Signup and view all the answers

What is a rare but serious adverse effect of aspirin in children with viral infections?

Reye's syndrome Signup and view all the answers

What is the result of salt and water retention caused by aspirin?

Electrolyte imbalance Signup and view all the answers

Which of the following is a therapeutic effect of NSAIDs?

Analgesia Signup and view all the answers

What is the characteristic of hypersensitivity reactions to aspirin?

Idiosyncratic and infrequent Signup and view all the answers

What is the syndrome caused by anti-inflammatory doses of aspirin?

Salicylism Signup and view all the answers

Which of the following is a characteristic of COX-2 inhibitors?

Less gastric mucosal damage Signup and view all the answers

What is the most common age group affected by acute salicylate poisoning?

Children Signup and view all the answers

What is a possible adverse effect of NSAIDs on the CNS?

Seizure precipitation Signup and view all the answers

What is the outcome of long-term therapy with high-dose aspirin?

Insidious onset hepatic injury Signup and view all the answers

What is the primary mechanism of action of nonsteroidal anti-inflammatory drugs?

Inhibition of COX-1 and COX-2 enzymes Signup and view all the answers

Which of the following is a possible interaction of NSAIDs with other drugs?

Decreased antihypertensive effect with β blockers Signup and view all the answers

Which of the following is NOT a therapeutic effect of analgesics?

Cure of the underlying disease causing pain Signup and view all the answers

What is a possible adverse effect of NSAIDs on the renal system?

All of the above Signup and view all the answers

What is the primary difference between opioid and non-opioid analgesics?

Mode of action in the CNS Signup and view all the answers

Which of the following is a characteristic of nonselective COX inhibitors?

They inhibit platelet function Signup and view all the answers

Which of the following NSAIDs is a preferential COX-2 inhibitor?

Celecoxib Signup and view all the answers

What is a possible adverse effect of NSAIDs on the gastrointestinal system?

All of the above Signup and view all the answers

Which of the following is a therapeutic effect of NSAIDs?

Antiinflammatory Signup and view all the answers

What is the mechanism of action of paracetamol?

Unknown, but thought to involve the CNS Signup and view all the answers

Which of the following is a common adverse effect of NSAIDs?

Gastrointestinal bleeding Signup and view all the answers

What is the role of slow-reacting substance of anaphylaxis (SRS-A) in the body?

Mediation of anaphylactic and allergic reactions Signup and view all the answers

Which of the following is an example of a propionic acid derivative NSAID?

Naproxen Signup and view all the answers

What is the role of leukotriene B4 in asthma?

It enhances chemotactic and chemokinetic responses in human neutrophils, monocytes, and eosinophils Signup and view all the answers

What is the effect of COX-1 and COX-2 inhibitors on lipoxygenases?

They inhibit lipoxygenases Signup and view all the answers

What is the therapeutic effect of prostacyclin (PGI2)?

Vasodilation and inhibition of platelet aggregation Signup and view all the answers

What is the function of lipoxin A4 (LXA4)?

Vasodilation and inhibition of neutrophil adhesion and chemotaxis Signup and view all the answers

What is the mechanism of action of aspirin?

Inhibition of COX-1 and COX-2 Signup and view all the answers

What is the therapeutic effect of prostaglandin E2 (PGE2)?

Analgesia and anti-inflammation Signup and view all the answers

What is the effect of leukotriene C4 (LTC4) on the bronchi?

Constriction of the bronchi Signup and view all the answers

What is the effect of thromboxane A2 (TXA2)?

Vasoconstriction and promotion of platelet aggregation Signup and view all the answers

What is the maximum dose of ketorolac that can be administered in a day?

90 mg Signup and view all the answers

What is the percentage of nimesulide bound to plasma proteins?

99% Signup and view all the answers

What is the primary use of nimesulide?

Short-term management of moderate pain Signup and view all the answers

What is a characteristic of nimesulide compared to other NSAIDs?

It is a weak inhibitor of PG synthesis and moderately COX-2 selective Signup and view all the answers

What is a common adverse effect of ketorolac?

All of the above Signup and view all the answers

What is the advantage of selective COX-2 inhibitors compared to traditional NSAIDs?

They cause less gastric mucosal damage Signup and view all the answers

What is the effect of selective COX-2 inhibitors on PGI2 production?

It is decreased Signup and view all the answers

What is the primary action of paracetamol?

Analgesic and antipyretic Signup and view all the answers

Why should selective COX-2 inhibitors be used with caution?

Due to their risk of cardiovascular events Signup and view all the answers

What is the effect of paracetamol on platelet aggregation?

It has no effect on platelet aggregation Signup and view all the answers

What is the plasma half-life of diclofenac?

2 hours Signup and view all the answers

What is a common adverse effect of diclofenac?

Headache Signup and view all the answers

What is the primary use of diclofenac?

Short-lasting painful inflammatory conditions Signup and view all the answers

What is the mechanism of action of diclofenac in terms of COX inhibition?

Somewhat COX-2 selective Signup and view all the answers

What is the dose of diclofenac for short-lasting painful inflammatory conditions?

100 mg BD Signup and view all the answers

What is the percentage of ketorolac excreted unchanged in urine?

60% Signup and view all the answers

Which of the following is a common adverse effect of piroxicam?

Heartburn Signup and view all the answers

What is not a known use of piroxicam?

Hypertension Signup and view all the answers

What is the mechanism of action of ketorolac in relieving pain?

Peripherally acting by inhibiting PG synthesis Signup and view all the answers

What is the plasma half-life of piroxicam?

2 days Signup and view all the answers

Mephenamic acid exerts its analgesic action in which parts of the body?

Both peripheral and central nervous systems Signup and view all the answers

What is a rare but serious complication of Mephenamic acid?

Haemolytic anaemia Signup and view all the answers

What is Piroxicam known for?

All of the above Signup and view all the answers

In which type of pain, is Mephenamic acid primarily indicated?

Muscle and joint pain Signup and view all the answers

What is the dosing frequency of Mephenamic acid?

250-500 mg TDS Signup and view all the answers

What is the primary route of elimination of propionic acid derivatives, including ibuprofen?

Both urine and bile Signup and view all the answers

Which of the following is a contraindication for prescribing ibuprofen?

Pregnancy Signup and view all the answers

What is the primary use of ibuprofen?

Both b and c Signup and view all the answers

What is a common CNS side effect of ibuprofen?

All of the above Signup and view all the answers

How much is the usual dose of ibuprofen?

400-600 mg Signup and view all the answers

What percentage of paracetamol is protein-bound in plasma?

about 1/4 Signup and view all the answers

What is the plasma half-life of paracetamol?

2–3 hours Signup and view all the answers

What is a common adverse effect of paracetamol?

nausea and rashes Signup and view all the answers

In which age group can paracetamol be used?

infants to elderly Signup and view all the answers

What is the dose of paracetamol for children?

10–15 mg/kg Signup and view all the answers

Why is paracetamol preferred over NSAIDs in certain cases?

it does not prolong bleeding time Signup and view all the answers

What is a use of paracetamol?

as an antipyretic Signup and view all the answers

How often should paracetamol be taken?

3–4 times a day Signup and view all the answers

What is the duration of action of paracetamol?

3–5 hours Signup and view all the answers

Why is paracetamol used in pregnant or lactating women?

because it is safer than NSAIDs Signup and view all the answers

Study Notes

Nonsteroidal Anti-Inflammatory Drugs (NSAIDs)

Definition: NSAIDs are a group of drugs that relieve pain, reduce inflammation, and lower fever.
Classification:
- Nonselective COX inhibitors
- COX-2 inhibitors (e.g. celecoxib, etoricoxib)
- Preferential COX-2 inhibitors (e.g. nimesulide)
- Analgesic-antipyretics with poor anti-inflammatory action (e.g. paracetamol)

Mechanism of Action

Inhibit cyclooxygenase (COX) enzymes, which convert arachidonic acid to prostaglandins and thromboxane
Reduce prostaglandin production, leading to decreased pain and inflammation
COX-1 is responsible for platelet aggregation and gastric mucosal protection, while COX-2 is involved in inflammation

Pharmacological Actions of Aspirin

Analgesic, antipyretic, and anti-inflammatory effects
Irreversibly inhibits thromboxane A2 synthesis, leading to prolonged bleeding time
Decreases synthesis of clotting factors in liver, increasing risk of bleeding
High doses can cause salt and water retention, vertigo, and tinnitus

Adverse Effects of Aspirin

Hypersensitivity and idiosyncrasy
Anti-inflammatory doses can cause salicylism, leading to dizziness, tinnitus, and electrolyte imbalance
Long-term therapy can cause hepatic injury and Reye's syndrome in children
Acute salicylate poisoning can cause coma and death

Features of NSAIDs

Nonselective COX inhibitors:
- Analgesic, antipyretic, and anti-inflammatory effects
- Increase risk of gastrointestinal bleeding and ulceration
- May cause renal salt and water retention, and delay or prolong labor
COX-2 inhibitors:
- Analgesic, antipyretic, and anti-inflammatory effects
- Less gastrointestinal toxicity
- May increase risk of cardiovascular events

Examples of NSAIDs

Salicylates (e.g. aspirin)
Propionic acid derivatives (e.g. ibuprofen, naproxen, ketoprofen)
Enolic acid derivatives (e.g. piroxicam)
Acetic acid derivatives (e.g. ketorolac)
Fenamates (e.g. mephenamic acid)
COX-2 inhibitors (e.g. celecoxib, etoricoxib)

Pharmacokinetics and Interactions

NSAIDs are well absorbed orally, metabolized in the liver, and excreted in the urine
May interact with other medications, such as diuretics, anticoagulants, and antihypertensives
May cause displacement interactions due to high protein binding

Contraindications and Precautions

NSAIDs are contraindicated in patients with active peptic ulcer, bleeding disorders, and hypersensitivity
Use with caution in patients with cardiovascular disease, hypertension, and kidney disease
Avoid use in pregnant women, especially in the third trimester

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Description

This quiz covers the interactions between different medications, including oral anticoagulants, sulfonylureas, and more. Learn about the risks and effects of combining these drugs.